The paint feeding device such as the coater, which is used for painting the vehicle body or various casings and the paint filling device, which supplies the paint to the coater, uses various types of paints (e.g. different colors). In such a case, changing valves to change colors, multiple types of paints are fed to the same feeding passage. When changing the colors, rinsing the passage to remove completely the remained paint used just before, then the next paint is fed to the passage.
In the case where the passage is not rinsed sufficiently, the paint includes contaminations (e.g. pollution or mixture) and the paint quality is lowered. Thus, to provide high painting-quality, it is important to rinse the paints remained in the passage and to remove them completely.
In the conventional devices, the long time rinsing may prevent the remaining of the paints. Unfortunately, taking a long time to change the paints lowers the workability, so such a measure actually does not work.
Various techniques of rinsing the paint feeding passage are studied and examined. For example, JP-H6-134359 A discloses the technique that uses the mixer which mixes the rinsing liquid and air to mix the micro air bubbles equally into the liquid, and rinses the passage efficiently.
Alternatively, the technique is carried out that a plurality of first valves for feeding the rinsing liquid and a plurality of second valves for feeding air are connected to the passage, increasing one-time feeding amount, and shorten the rinsing time.
Unfortunately, the conventional techniques need large equipment such as the system equipped with the mixer or the plurality of valves.
Moreover, in the conventional techniques, it is thought that the more discharge amount of the rinsing liquid, the higher rinsing quality is obtained, so that when rinsing the paint feeding passage, the time chart of changing the valves is set for providing the rinsing liquid as much as possible in short time. Therefore, the liquid is wasted and the used amount of the liquid increases uselessly.